Stay on the tutorial leaving open targets "sell an item" and "giving a citizen an item". Do not collect the reward for doing these two tasks. Instead, repeat the three tutorials collect 50 food, water and board a Dweller. By doing so, you will receive caps or Lunch Box.

Time-Cheat

To use this little cheat / bug you have to switch the internal clock of your iPhone / iPad from automatically to manuel.

Then go into the game and double-tap the home button.

You go back to your internal clock and turn a little to as long as you want.